1. Field of the Invention
The present invention relates to a one-way clutch including a locking element accommodated in a pocket defined in an inner peripheral surface of an outer race, the locking element being urged by a spring toward an outer peripheral surface, thereby inhibiting the relative rotation of an inner race and the outer race relative to each other in one direction, and permitting the relative rotation of an inner race and the outer race relative to each other in the other direction.
2. Description of the Related Art
Such one-way clutch is known, for example, from Japanese Patent Application Laid-open No. 11-51091. In this one-way clutch, a roller is used as the locking element. When the inner race and the outer race are rotated in one direction relative to each other, the roller is forced into and locked in a wedge-shaped space between both the races by a resilient force of the spring. When the inner race and the outer race are rotated in the other direction relative to each other, the roller is moved against the resilient force of the spring and thus unlocked.
Japanese Patent Application Laid-open No. 11-182588 describes a one-way clutch in which a sprag is used as a locking element. The sprag is a member of a radially centrally constricted shape, and is swingably supported at its constricted portion by a retainer and a ribbon spring disposed between an inner race and an outer race.
The one-way clutch in which the roller or the sprag is used as the locking element, suffers from the following problem: The locking element is brought into line contact with the inner race and the outer race and for this reason, the surface pressure at contact portions is increased to provide an adverse effect to the durability. In addition, the one-way clutch using the sprag suffers from a problem that its structure is complicated since it requires a retainer and a ribbon spring for swingably supporting the sprag, resulting in increased cost.
The present invention has been achieved with the above circumstances in view, and it is an object of the present invention to provide a one-way clutch, wherein a load acting on the locking element can be reduced in a simple structure.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a one-way clutch comprising locking elements each accommodated in each of pockets defined in an inner peripheral surface of an outer race, each of the locking elements being urged by a spring toward an outer peripheral surface an inner race, thereby inhibiting the relative rotation of the inner race and the outer race relative to each other in one direction, and permitting the relative rotation of the inner race and the outer race relative to each other in the other direction, wherein each of the locking elements is formed with a partially columnar support projection and an engage portion comprising a convex curved surface, the support projection being swingably supported in and substantially in face contact with a partially columnar support recess defined in the corresponding pocket, the engage portion being in line contact with an outer peripheral surface of the inner race comprising a columnar surface.
With the above arrangement, each of the locking element is swingably supported in the partially columnar support recess defined in the corresponding pocket, with the partially columnar support projection formed on the locking element being substantially in face contact with the partially columnar support recess. Therefore, the surface pressure on contact portions of the locking element and the pocket can be reduced as compared with the surface pressure of the line contact, leading to an enhancement in durability of the locking element and the outer race. In addition, the engage portion comprising the convex curved surface formed on the locking element is in line contact with the outer peripheral surface of the inner race comprising the columnar surface and hence, the inner race and the outer race can be locked at any phase, unlike a one-way clutch in which a pole and a notch are brought into engagement with each other.
According to a second aspect and feature of the present invention, in addition to the arrangement of the first feature, there is provided a one-way clutch wherein the outer race is formed integrally with a stator of a torque converter and supported on stator-supporting members with a pair of thrust bearings interposed therebetween, and the locking element accommodated in each of the pockets in the outer race is prevented from being fallen off by the thrust bearings.
With the above arrangement, the outer race of the one-way clutch is formed integrally with the stator of the torque converter and hence, the number of parts can be reduced, as compared with a case where the outer race and the stator are separate members. In addition, the falling-off of the locking element accommodated in each of the pockets in the outer race is prevented by the pair of thrust bearings for supporting the outer race on the stator-supporting members. Therefore, a special member for retaining the locking element in each of the pockets is not required, leading to a reduction in number of parts, but also the width of each of the locking elements can be increased up to the entire width of the corresponding pocket, whereby the surface pressure acting on the locking element can be reduced, and the number and size of the locking elements can be reduced.
A pole 53 in the embodiment corresponds to the locking element of the present invention, and a boss 22 and an auxiliary-driving shaft 29 in the embodiment corresponds to the stator-supporting members.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.